title: Photosystem 2 effective fluorescence cross-section of cyanobacterium Synechocystis sp. PCC6803 and its mutants.
abstract: The effective fluorescence cross-section of photosystem 2 (PS2) was defined by measurements of chlorophyll a fluorescence induction curves for the wild type of the unicellular cyanobacterium Synechocystis sp. PCC6803, C-phycocyanin deficient mutant (CK), and mutant that totally lacks phycobilisomes (PAL). It was shown that mutations lead to a strong decrease of the PS2 effective fluorescence cross-section. For instance, the effective fluorescence cross-section of PS2 for wild type, CK and PAL mutants excited at λ(ex)=655 nm were found to be 896, 220 and 83 Å(2) respectively. Here we present an estimation of energy transfer efficiency from phycobilisomes to the pigment-protein complexes of PS2. It was shown that the PS2 fluorescence enhancement coefficient reaches a maximum value of 10.7 due to the energy migration from phycobilisomes. The rate constant of energy migration was found to be equal to 1.04 × 10(10) s(-1).
authors.affiliation: Department of Biophysics, Biological Faculty of the M.V. Lomonosov Moscow State University, 119991 Moscow, Russia. emaksimoff@yandex.ru
authors.forename: Eugene G
authors.initials: EG
authors.lastname: Maksimov
authors.forename: Fedor I
authors.initials: FI
authors.lastname: Kuzminov
authors.forename: Ivan V
authors.initials: IV
authors.lastname: Konyuhov
authors.forename: Irina V
authors.initials: IV
authors.lastname: Elanskaya
authors.forename: Vladimir Z
authors.initials: VZ
authors.lastname: Paschenko
mesh_terms: D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D000077194:Chlorophyll A; D004735:Energy Transfer; D009154:Mutation; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D045524:Phycobilisomes / Q000378:metabolism; D010798:Phycocyanin / Q000235:genetics / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D046939:Synechocystis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D045524:Phycobilisomes; D010798:Phycocyanin; D002734:Chlorophyll; D000077194:Chlorophyll A